Automated analysis of biological specimens requires a high degree of performance and consistency from the optical and electronic imaging systems. Image processing analyses of biological specimens use various segmentation algorithms and morphological operations that depend on consistent imagery for accurate and repeatable results. Performance of image collection systems comprised of imaging optics and detector electronics and a digital processor can be primarily characterized by three measurements. These measurements include modulation transfer function or frequency response, linearity and the signal to noise ratio. Image processing systems used for biological analysis may be used to make or help make diagnoses regarding the state of infections or disease of human subjects. Therefore, these diagnoses must be of the highest degree of integrity possible. Accordingly, the imaging systems used to capture images for processing must be checked frequently during operation to ensure highly consistent and accurate performance. The present invention provides techniques and apparatus used to characterize such systems during operation.